A cassette insertion control method, wherein when a cassette (1) is sent to the storage part (41) of a garage (8a), the cassette (1) is tilted without positioning the garage (8a) and the cassette (1) to oppose to each other, and sent to the front opening part (40) of the garage (8a) from a tip corner part (45) of the cassette (1), thereby to securely store the cassette (1) in the garage (8a). Thus, even if the accuracy of the stop position of a picker running in a direction parallel with the arranged direction of the garage is not so high, the cassette can be securely stored in the garage.